1. Field of the Invention
The present invention relates to a novel Hericium erinaceum NEU-1L strain (deposit number: KCTC 12499BP), a lectin binding specifically to sialic acid which is produced thereby, and a use of the same.
2. Description of the Related Art
Lectin is one of the proteins that can bind to glycoconjugates, which is endogenous in a variety of organisms from microorganisms to higher animals. It is known that lectin is involved in various life phenomena including protein quality control, host-pathogen interaction, cell-cell communication, inflammation, immune response, cancer progression, and development by binding specifically to glycoconjugates (Lam and Ng, 2011. Appl. Microbiol. Biotechnol. 89, 45).
Lectins are multivalent carbohydrate binding proteins that display neither catalytic activity nor antibody like characteristics. Lectin was first isolated from Ricinus communis by the Russian scientist Sillmark in the late 19th century. Since then, 40 kinds of lectins including Concanavlain A (ConA) have been identified, studied, and used in various fields. According to the recent advancement of molecular biology and biochemistry, lectins are classified into many groups according to their nucleotide sequences and protein structures. According to origin, lectins are also classified into plant lectin (plant lectin families) and animal lectin (invertebrate/vertebrate lectin families). Vertebrate lectins are divided into such groups as C-type (mannose-binding lectin, MBL), S-type (galectin: β-galactoside-binding lectin), P-type (mannose-6-phosphate bind lectin), and I-type (selectin) according to their characteristics, and belongs to the Pentraxin group represented by a cyclic pentameric structure according to their protein structure. In spite of such an abundance of lectin, invertebrate/vertebrate lectin families functioning somehow in physiological metabolism in cells have been rarely reported, compared to plant lectins. Therefore, plant lectins extracted from the natural system have been widely applied to diagnose blood type and applied thereof by using their glycan binding specificities (Lehmann et al., 2006, Cell. Mol. Life Sci. 63, 1331).
Plant lectins are identified in almost every part of a plant including leaves, stems, roots, flowers, and pollens, and even in seeds and bulbs which can be harvested. Therefore, plant lectins have been easily purified from plants. In plants, lectins are involved in a variety of activities and functions such as immune function, self-defense from harmful insects, self-defense from animals by causing allergic reaction, anti-fungal activity, anti-viral activity, colonization in a specific region of symbiotic microorganism by cell/cell interaction between plants and microorganisms, delivery and preservation of nutrients and metal ions, protecting plants from coldness, acting as a partner to increase enzyme activity in cells, and trafficking of glycoproteins, etc. These activities and functions are accomplished by glycan specific binding activities of lectins, according to the previous reports (Lehmann et al., 2006, Cell. Mol. Life Sci. 63, 1331; Singh et al., 2010 Crit. Rev. Biotechnol. 30, 99).
By using such a glycoconjugate specific binding activity of a lectin, a lectin is believed to be effectively used for the early diagnosis of a specific disease by observing the changes of glycoproteins, glycolipids, and oligosaccharides presented on the cell surface, and further studied with animal tests to cope with a disease by boosting the in vivo immune system by the agglutination with glycoconjugates of the cell surface of the key cells to cause a disease or of the cell surface of viruses and microorganisms. Along with the recent development of optical microscope techniques and the chemical synthesis methods of various fluorescent probes, the glycan specific binding activity of lectin is a useful tool for application of glycan biomarker detection for the early diagnosis of cancer cells, the identification of the location of a specific endogenous glycoprotein, the measurement of glycan-mediated cell/cell interaction, and scanning of image of intracellular invasion of viruses and microorganisms, owing to its usability in recognizing glycoconjugates on the surface of specific cells, viruses, and microorganisms. The commercialized lectins nowadays are extracted from various sources such as plants, animals, and microorganisms, and they are useful for measuring the basic monomer of sialic acid (Neu5Ac, N-acetaylneuraminic acid), galactose (Gal), N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), fucose (Fuc), mannose (Man), rhamnose (Rha), xylose (Xyl), and glucose (Glc) (Lehmann et al., 2006, Cell. Mol. Life Sci. 63, 1331; Singh et al., 2010 Crit. Rev. Biotechnol. 30, 99; Kajiwara et al., 2010, Microbes Environ. 25, 152).
However, owing to the variety of glycan structures including alpha-linkage and beta-linkage, and monomer composition of glycans, hundreds of or thousands of different glycan structures can be theoretically found in a natural system. Nevertheless, the number of lectins identified so far are limited to detect or to measure these types of glycoconjugates. In particular, the commercialized Maackia amurensis (MAA), Sambucus nigra (SNA), and Limulus polyphemus lectins are known to bind specifically to the specific sialic acid (Neu5Ac). However, a limited number of sialic acid-binding lectins are available rather than other sugar binding proteins for Gal and GlcNAc, etc. In addition, these sialic acid binding lectins sometimes do not distinguish α(2,3)-, α(2,6)-, and α(2,8)-sialic acid linkages precisely, due to non-specific binding activities.